1. Field of the Invention
The present invention is related to an emergable watermark superimposing method, an emergable watermark superimposing apparatus, and an emergable watermark superimposing system.
2. Description of the Related Art
Problems occur in infringement of copyright which is caused by illegally coping paper documents, and illegal acts (will be referred to as “attacks”) with employment of elaborate copied articles, which can be actually realized due to progress in copying techniques.
As techniques capable of opposing these attacks, there are printing techniques for printing characters and the like which restrain copying of paper documents. That is, when the relevant paper documents are copied, for instance, characters such as “COPY” appear on copied documents, which clearly indicate that the copied documents constitute copied articles. The above-described printing techniques are utilized m, for example, certificates and the like which are issued by self-governing bodies.
As publications for disclosing the above-described techniques, for instance, U.S. Pat. No. 7,359,087 specification is present. This publication describes “In a print control apparatus 1 that has a printing device 6 to print a document, a CPU 2 combines a remaining pattern image composed of dots larger than a minimum dot size readable by a color copying machine and a vanishing pattern image composed of dots having the same size as the larger dot and dots smaller than the minimum dot readable by the color copying machine to produce a reproduction checking image and causes the printing device 6 to print the reproduction checking image along with document print data on paper.” (refer to Abstract).
Also, techniques for retraining not copying of paper documents, but copying of moving images have been proposed. For example, US Patent Application Publication 2006/0188012 specification describes “This invention relates to an apparatus for encoding data or the like, which disables the data to be copied in a condition where its good quality is maintained without deteriorating a quality of an output owing to the data before being copied. Synchronization signals VD and HD are separated from the analog image data Van are delayed and supplied to a clock generation circuit 1133 where a clock CLK is generated in a rage of an effective screen based on the synchronization signals. This clock signal CLK is shifted vertically and horizontally so that a phase of image data Vdg1 output from an A/D converter 1134 is also shifted. In this image data Vdg1, a signal-deteriorating factor is generated. An encoding section 1135 performs encoding by sampling, conversion encoding, and the like. By-shifting the phase of the image data Vdg1, a sampling position and/or a block position are caused to be shifted from a position where obtaining original encoding data relative to the image data Van1, thereby generating significant deterioration in the encoding section 1135.” (refer to Abstract).